1. Field of the Invention
The present invention is directed to the field of fuel consumption measurement and more specifically to the area of such measurement as applied to internal combustion engines utilizing hydraulically driven fuel injectors.
2. Description of the Prior Art
Techniques for deriving fuel consumption information from aspirated internal combustion engines is conventionally performed by inserting a fuel flow sensor in the fuel line since all fuel pumped through such a line is consumed by the engine. Such a fuel flow sensor is illustrated in U.S. Pat. No. 3,867,840.
The obtaining of fuel consumption information from internal combustion engines which employ injector valves has required other measuring techniques since only a portion of the fuel travelling in the fuel line, under pressure, is actually consumed. The portion that is not injected into the engine is returned to the fuel storage tank.
One technique used to derive fuel consumption information from internal combustion engines which employ electronically controlled fuel injectors, involves monitoring the length of pulses sent to open injector valves. This technique is shown in U.S. Pat. No. 4,002,062 and relies on the assumption that the injector valves provide a certain volume of fuel to the engine in response to each pulse.
Injectors that are mechanically driven from a cam shaft on an associated engine are opened a predetermined amount for the injection of fuel for periods of time that are directly related to the speed of the engine. Throttle variations are translated to fuel pressure variations at the injector. U.S. Pat. No. 4,062,230 describes a technique for measuring fuel consumption information in such an environment by monitoring pressure on the line.